It is well known that the superheavy oil emulsion fuels give stable emulsion fuels when used together with additives, such as emulsifiers, stabilizers, and fluidizing agents, and various excellent emulsifiers to be used in emulsion fuel compositions have been developed (See Japanese Patent Laid-Open No. 1-185394, U.S. Pat. No. 5,024,676, and Japanese Patent Laid-Open No. 1-313595). However, even when these additives including emulsifiers, stabilizers, and fluidizing agents are used, the concentration of the superheavy oil in the superheavy oil emulsion fuel is at most 77% by weight. A superheavy oil emulsion fuel which is stable and has good fluidity is easy to handle. As the concentration of the superheavy oil increases, the thermal energy loss by water decreases, thereby making the resulting emulsion fuel more valuable. Also, a high superheavy oil concentration is beneficial because it can be diluted upon use where necessary.